Composite reticulated foam-textile cleaning pad

ABSTRACT

A composite cleaning pad is provided which incorporates a sheet of open-celled reticulated, hydrophillic polyurethane foam which integrally incorporates silane-coupled abrasives and a gelled aqueous phase and a textile sheet which covers a surface of the foam sheet and is bonded thereto.

This is a division of application Ser. No. 621,376, filed June 18, 1984.

BACKGROUND OF THE INVENTION

The problems encountered in producing foam-based sheets or pads designedto meet household cleaning needs have been addressed by a variety ofproducts. Polyurethane foam-based sponge products which have beendisclosed fall into two general classes, which may be designated as dryand moist. Dry sponge products are disclosed by Strickman et al in U.S.Pat. Nos. 4,271,272 and 4,421,526. These products are formed by reactingisocyanate-capped polypropylene glycol resins with small amounts ofwater and organic catalysts, followed by stirring powdered detergentsand/or abrasives into the foaming resin. Since the molar ratio of waterto free isocyanate groups on the resin is generally adjusted to about0.5 or less, the cured foam which is obtained is dry. This results inadditives such as abrasives and detergents being largely deposited inthe cell voids, thus reducing the sponge's absorbency. When the spongesare remoistened, the additives must re-emulsify prior to becomingavailable for application in a cleaning operation.

The preparation of open-called, hydrophilic or "moist" polyurethanefoams by the reaction of specially-formulated prepolymer isocyanateresins with large molar excesses of water without the need for addedcatalysts or cross-linking agents is disclosed in U.S. Pat. Nos.3,890,254; 4,137,200 and 4,160,076. These resins permit the introductionof large amounts of solids into the form matrices via preformed aqueousslurries of solid particles which are subsequently reacted with theprepolymer resin in order to foam it into the desired specialty product.The finished foams are very hydrophilic, or water-absorbent, due to theentrapment of excess water within the cell walls.

U.S. Pat. Nos. 3,833,386; 4,066,394; 4,066,578; 4,309,509; and 3,343,910describe the incorporation into hydrophilic forms of sinterable ceramicmaterials, water-softening minerals such as zeolites, flame retardants,ordorant-containing waxes and fine abrasives, respectively. In order toproduce solids-loaded foams for use as polishing pads, sachets,water-softening sponges, cushions and the like, the weight ratio ofaqueous phase to resin must be maintained at a value low enough so thatthe foam matrix exhibits satisfactory overall integrity. Increasing theweight of additives in foamed products formed by this method necessarilyrequires the use of higher ratios of water to prepolymer resin, which inturn attenuates the polymeric cellular matrix which is furtherembrittled by the introduction of the solids. Surfactants which resultin a highly reticulated, open-celled matrix also reduce the absolutestrength of the foam due to the removal of cell window membranes.Although reticulated, open-celled, hydrophilic polyurethane foams whichare highly loaded with particulate abrasives are desirable due to theiroptimal cleaning power, when the weight ratio of dispersed abrasives inthe aqueous phase to the presently-available prepolymer resins exceeds acertain value, the resultant foams will become friable. These foams areunsuitable for use as cleaning pads and sheets due to their low tensilestrength which causes the cured foams to flake or crumble during use.

Thus, it is an object of the present invention to provide cleaning padsor sheets comprising a moist, hydrophilic polyurethane foam whichincorporates a large amount of particulate abrasive and which furtherincorporates effective amounts of detergent surfactants.

It is another object of the present invention to provide resilientcleaning pads or sheets suitable for cleaning a wide variety of surfacescomprising open-celled, highly-reticulated, hydrophilic polyurethanefoams of low tensile strength which comprise abrasive particles anddetergents integrally incorporate within the cellular matrix of thefoam.

Other objects and advantages of the present invention will becomeapparent from the following description and appended claims.

BRIEF DESCRIPTION OF THE INVENTION

The objects of the present invention are accomplished by a compositecleaning pad incorporating opposed foam and textile surfaces. The padcomprises a dense sheet of open-celled, reticulated hydrophillicpolyurethane foam, the cell walls of which integrally incorporate agelled aqueous emulsion comprising one or more nonionic surfactants anda particulate abrasive coupled into the walls. One surface of the foamsheet is substantially covered by a textile sheet which is integrallybonded thereto.

The pad is prepared by foaming and curing a suitable polyurethaneprepolymer resin in contact with the textile sheet. The resin is foamedwith an aqueous reactant phase comprising a slurry of solid abrasiveparticles, a coupling agent, a nonionic surfactant and a gelling agent.The coupling agent can be a silane comprising reactive functionalitieswhich chemically bind the abrasive particles into the cell walls duringthe foaming process, thus imparting long-lasting scouring power to thecleaning pads. The aqueous phase comprises an amount of water in excessof that required to foam the resin. This excess water is also integrallyincorporated into the cell walls of the cured foam as an aqueous phase.The nonionic surfactant will be selected from at least those whichfunction to produce the open-celled, reticulated foam matrix. Thenonionic surfactant may also include foam-formers such as amine oxidesand foam-control agents such as silicone-based surfactants. Preferably,an effective detergent amount of an anionic surfactant will also beincorporated into the aqueous phase.

The aqueous phase incorporated into the cell walls of the foam sheetswill be in the form of a gel. The gel can be produced by the addition ofan effective amount of an inorganic gelling agent to the aqueousreactant phase used to foam the resin. The gelling agent, e.g. particlesof wollastonite or smectite clay, functions to (a) stabilize thedispersion of the abrasive solids in the aqueous reactant phase, (b)control the cell size, (c) strengthen the connective matrix of the foam,and (d) impart a degree of buffing or polishing power to the foam sheet.

The textile sheet performs the dual function of reinforcing the foamsheet and providing a nonabrasive cleaning and wiping surface on thepad. When moistened, these double-surfaced pads are useful for cleaninga wide variety of porous and nonporous household or workplace surfaces,such as countertops, appliances or bathroom fixtures, including surfacesformed of wood, linoleum, metal, porcelain, glass, plastics or ceramics.

Although polyurethane foams useful in the present invention may beformed employing aqueous slurries which comprise up to about 80% byweight of the silane-treated particles, an amount of abrasive equal toabout 45-75%, preferably about 50-70% of the total slurry weight ispreferred, since this range of particles can be firmly bound to the cellwalls and imparts effective scouring power to the cleaning pad.

Therefore, the present cleaning pads comprise a solids-loaded foam whichis formed by mixing the aqueous slurry with a suitable prepolymer resinso that the final mole ratio of water to the total free isocyanategroups on the prepolymer molecules is within the range of about 5-100:1.These amounts of water react with the free isocyanate groups to releasecarbon dioxide which blows the prepolymer into a dense, cross-linked,open-celled foam which is rendered hydrophilic by entrapment of excesswater in the cell walls of the foam. In the practice of the presentinvention, this entrained aqueous emulsion will exist in the cell wallsin the form of a gel. The aqueous phase will also comprise emulsifiedsurfactants, and may further comprise emulsified silicone fluids.

While the hydrophilicity of the present cleaning sheets is to beexpected in view of the chemical composition of the prepolymer resin andthe excess of water used to foam it, it has unexpectedly been found thatthe foam portion of the composite will readily and effectively absorband hold large amounts of viscous hydrophobic liquids, such as oilychemicals, cooling oil, lubricating oil, mineral oils and the like, thuseffectively cleansing a household or workplace surface of greasy soil.This effect is thought to be due in part to the strong wicking actionexerted by the connecting passages between the cells. These passages areformed during foaming by the surfactant-assisted opening of the cellwindow membranes. These membranes do not tear away completely, butremain connected to the reticulated foam matrix to provide tubularpassageways which exert a strong capillary action on a stain or liquidspill, even when the liquid has been partially absorbed by poroussurfaces such as wood or concrete.

In preferred foams prepared according to the present invention, the tornwindows of the cells cure with irregular or jagged edges. These edgesact to further increase the effective surface area of the foam shredsand enhance the already strong wicking action of the composition. Theirregular, or reticulated surface of the foam sheet also increases thescouring power imparted by the abrasive particles.

Both the surface-and-deep-cleaning activity of the present compositecleaning sheets are enhanced by incorporating an effective detergentamount of one or more surfactants in the aqueous phase used to form thefoams. The water in excess of that required to foam the resin isintegrally incorporated within the cell walls of the foam. This water,along with the surfactants and other additives emulsified therein, isreleased when the pad is wetted and contacted with the soiled surfaceunder conditions of pressure, such as by rubbing the foam or textileside of the cleaner over the soiled surface. The surfactants act to foamthe aqueous phase and to wet oily dirt. The surfactant then functions todisperse the grease in the aqueous phase, which is reabsorbed by theporous cleaning sheet.

As used herein, the term "cell walls" is intended to include any portionof the polymeric framework of the present foams, including theconnective matrix and the cell window membranes.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a photographic sectional view of a coated layer formedaccording to the invention.

FIG. 2 is a photographic magnified portion of the foam layer of FIG. 1.

FIG. 3 is another photographic sectional view of a coated layer formedaccording to the invention.

FIG. 4 is a photographic magnification of a portion of the foam layer inFIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The composite cleaning pads of the present invention are prepared by aprocess comprising forming an aqueous slurry which includes solidabrasive particles which have been treated with a silane-coupling agent.The term "pads" as used herein is intended to include any bodyappropriately shaped so as to incorporate both a foam and a textilesurface, including but not limited to shaped pads for manual applicationor for application by power-driven units, as well as thin towel-likecleaners. The slurry further will include an amount of a nonionicsurfactant effective to form an open-celled, reticulated foam uponreaction of the aqueous phase with a water-foamable polyurethaneprepolymer resin. The nonionic surfactant mixture is also preferablycompounded so as to allow the aqueous phase formed when the cleaningsheet is moistened to disperse or dissolve greasy spills or stains. Oneor more gelling agents will also be included in the slurry in an amounteffective to control the cell size of the finished foam, to stabilizethe aqueous phase remaining within the cell walls, and to strengthen thecellular structure of the foam.

The aqueous phase can further comprise additional foam-forming andstructuring agents such as silicone fluids, and additional surfactanttypes which also act to build the cleaning power of the finishedcomposition and to stabilize the moist foam matrix. The fully-formedaqueous slurry is then combined with a water-foamable prepolymer resinand the reaction mixture allowed to foam and cure in contact with atextile layer. A composite cleaning pad results which comprises aself-cross-linked, open-celled, polyurethane sheet, one face of which istightly bound to the textile sheet via intermingling of the cured foammatrix with the textile fibers.

A commercially available class of water-foamable prepolymer resins whichyield cross-linked, hydrophilic polyurethane foams upon the addition ofstoichiometric excesses of water are those belonging to the Hypol®series (W. R. Grace & Co.; FHP 3000, 2000, 2000 HD, 2002) which aregenerally described in U.S. Pat. No. 4,137,200, the disclosure of whichis incorporated by reference herein. These liquid resins are prepared bycapping mixtures of low molecular weight polyols having 3-8 hydroxylgroups and polyoxyethylene diols with toluene diisocyanate. The cappedalcohol mixtures have an average number of free isocyanate groups permolecule which is equal to two or more, i.e., 2-8.

These resins possess molecular weights within the range of about1300-1400 and have about 1.5-2.5 mEq./g. of free isocyanate groups. Uponbeing contacted with a molar excess of water, the isocyanate groupshydrolyze to release carbon dioxide gas, thus foaming the resin withoutthe need for added catalysts or blowing agents. The free amino groupsformed by the hydrolysis reaction react with unhydrolyzed isocyanategroups to form ureido groups which crosslink and stabilize the foam,while entrapping a part of the excess water in the cell walls, where itacts to impart hydrophilic properties to the foam. The compatibility ofthe foam matrix with large molar excesses of water is a necessaryrequirement of resins useful in the practice of the present invention,since large amounts of water are needed to uniformly introduce largeamounts of abrasive material into the matrix.

Other poly-C₂ -C₃ -alkyleneoxy glycols capped with aromatic isocyanatesmay be prepared which possess a suitable balance between their extent ofcross-linking prior to foaming and their ability to cross-link or tofurther cross-link during foaming (due to the presence of more than tworeactive isocyanate groups per resin molecule), so as to be useful inthe practice of the present invention over the entire range of solidsand surfactant content. These prepolymer resins are prepared bypolymerizing ethylene oxide to yield polyalkylenoxy polyols having amolecular weight of about 900-1100. These polyols are reacted with astoichiometric excess of a polyisocyanate. Suitable isocyanates includetoluene diisocyanate, triphenylmethane-4,4',4"-triisocyanate,benzene-1,3,5-triisocyanate, hexamethylene diisocyanate, xylenediisocyanate, chlorophenylene diisocyanate and mixtures thereof. Theuseful resins recovered have a somewhat lower number of mEg of freeisocyanate groups (NCO) per gram of resin than do the Hypol® resins,e.g. 1.3-1.5 mEq NCO/gram and exhibit a substantially higher tensilestrength when foamed and cured at ambient temperatures to incorporatehigh percentages of dispersed abrasives.

One such commercially available self cross-linking resin is TRE STD®prepolymer resin (Twin Rivers Engineering Co., East Booth Bay, ME),which forms acceptable foams upon reaction with at least astoichiometric excess of water without employing a low molecular weightpolyol component to raise the average number of free isocyanate groupsper glycol ether molecule to above two. TRE STD® resin has an averagefree isocyanate content of about 1.4 mEq./gram, comprises a polyolcomponent having an average molecular weight of about 1000, exhibits aviscosity at 32° C. of 4700 cps and solidifies at 15.5° C. In thepractice of the present invention, useful foams may be formed employinga weight ratio of water to prepolymer resin of 0.5-2:1, preferably0.75-1.5:1. These ranges yield a mole ratio of water to free isocyanategroups of about 20-80:1, preferably about 30-60:1.

Particulate abrasive solids are employed as components of the presentcleaning compositions and are dispersed and bound throughout the foammatrix by silane-coupling agents as described below. The choice ofabrasive material may be made from a wide variety of materials ofadequate hardness and of a particle size range which will enable them toeffectively scour soiled surfaces. The solids will preferably compriseabout 45-75% by weight of the aqueous reactant phase, most preferablyabout 50-70%. The weight ratio of abrasive to prepolymer which may beused is limited only by the ability of the foamed polymeric matrix toretain the abrasive particles without undue separation and loss of thesolid during preparation, shipping or use. Preferably, the weight of theabrasive used will be from about 100-500% of the prepolymer weight, mostpreferably 150-300%. These high weight ratios of water and abrasive toresin yield soft, flexible, extremely dense foams, which after curing atambient temperatures, exhibit densities of from about 0.2-0.4 g/cc,preferably about 0.25-0.35 g/cc, and breaking strengths of about 300-400g (unreinforced).

A preferred abrasive for use in the foams of the present invention isF-4 Feldspar® (170-200 mesh) available from International Minerals andChemical Corporation, Mundelein, Ill.

Due to the necessity of employing a silane-coupling agent to effectivelybind the preferred amounts of abrasive particles to the foam matrix,abrasive particles are preferably chosen from those substances whichpossess sufficient free surface Si--OH or Al--OH groups to form reactivesites for the silane-coupling agents. Among the substances that meetthis requirement are minerals such as the feldspars, quartz, aluminas,diatomaceous earths, sands, glasses, naturally-occurring and syntheticzeolites, zircon, carborundum, pumice and the like, which may be usedsingly or in mixtures. The silane-treated abrasive solids are introducedinto the present cleaning compositions as components of the aqueousreactant phase, in which they are suspended prior to the foamingreaction, as described hereinbelow.

The compositions of the present invention will also include a minor buteffective amount of a silane-coupling agent which functions to bond toboth the polyurethane matrix and the surface of the particles of theinorganic abrasive, thus chemically-coupling the abrasive into thepolymeric matrix and preventing the abrasive particles from separatingfrom the foam matrix during packaging or use. Silane-bound solidparticles also clump less readily and so are more evenly dispersedthroughout the matrix during foaming.

Useful silane-coupling agents may be selected from members oforganosilicon monomers such as aminoalkyl(trisalkoxy)silanes which arecharacterized by the formula R--SiX₃, wherein R is an organofunctionalgroup attached to silicon in a hydrolytically stable manner and Xdesignates hydrolyzable groups which are converted to silanol groupsupon hydrolysis. Most commonly, R comprises 3-aminopropyl or3-ureidopropyl moiety which may be further separated from the silicongroup by one or two --NH(CH₂)_(n) -- moieties wherein n=1-2. PreferablyX is an alkoxy group selected from the group consisting of methoxy,ethoxy, 2-methoxyethoxy or is acetoxy. Preferred silane-coupling agentsare commercially-available from Union Carbide as the A1100-A1160 serieswhich includes 3-aminopropyltriethoxysilane,3-aminopropyltrimethoxysilane (also available from Dow Corning asZ-6020), N-2-aminoethyl-3-aminopropyl-trimethoxysilane, or3-ureidopropyl-triethoxysilane.

A thick slurry of the abrasive particles is prepared with about 50-70%by weight of the total water used to form the aqueous phase. The aqueousslurry, which may contain up to about a 500% weight excess, preferablyan about 300-400% excess of abrasive particles, is then treated with anamount of the silane-coupling agent equal to about 0.1-5% by weight ofthe amount of slurried solid. Completion of the hydrolysis reaction isassured by warming the slurry to at least about 21°-32° C. at whichpoint the other components of the aqueous phase may be added, along withthe remainder of the water. When the abrasive solid particles are coatedin this fashion, the free amino groups of the coupling agent bind to thepolymeric chains of the substrate during the foaming step, i.e., whenthe aqueous reactant phase and the polyurethane prepolymer are mixedtogether.

When foamed with appropriate excesses of water comprising slurried,coupled solids and the appropriate surfactants, these prepolymer resintypes will afford open-celled foam sheets which possess many of theproperties essential for use in composite cleaning pads. However, withinthe preferred range of solids, e.g. about 100-500% of the prepolymerweight, the strength of the cured foam sheets often falls to a levelinsufficient to maintain their integrity even after reinforcement withthe textile layer. The observed cracking and crumbling of such cleanersduring use is believed to be due to the attenuation and embrittlement ofthe open-celled foam matrix by the particulate solids and the largeamounts of water needed to suspend the solids.

Surprisingly, we have found that cured foams exhibiting satisfactorystructural integrity for use in the present composite cleaning pads canbe prepared if a gelling agent is added to the aqueous phase in anamount effective to gel the aqueous emulsion which is incorporated intothe cell walls of the cured foam. In practice, the aqueous reactantphase is gelled by the addition of an effective amount of one or moreorganic or inorganic gelling agents. Organic gelling agents useful inthe practice of the present invention include carboxymethycellulose,polyvinylpyrrolidone and polymeric organic waxes. The useful polymericwaxes include ethylene acrylate copolymers, ethylene acrylic acidcopolymers, and polyethylene (e.g. oxidized polyethylenes). Thesematerials are commercially available in the form of aqueous emulsions ordispersions, e.g. from Allied Chemical, Morristown, NJ, as the A-CCopolymer and A-C Polyethylene series, such as A-C Copolymer 540, A-CCopolymer 580 and A-C Polyethylene 617 and 629. The aqueous dispersionsmay also comprise small amounts of surfactants, i.e. anionic or nonionicsurfactants, which aid foam reticulation. The wax dispersions may beadded directly into the slurried solids, or pretreated with othergelling agents, surfactants and the like.

Preferably, the inorganic gelling agents employed will comprise those ofnatural or synthetic of mineral origin. Preferred gelling agents are thesmectite clays such as the saponites and the montmorillonite colloidalclays such as Veegum® (Vanderbilt Minerals, Murray, KY) or Magnabrite®(American, Colloid Co., Skokie, IL). Inosilicates can also be used,alone or in combination with the clays to produce fine open-celledfoams. Preferred inosilicates are the naturally-occurring calciummetasilicates such as wollastonite, available as the NYAD® wollastoniteseries (Processed Minerals Inc., Willsboro, NY), of which NYAD® 400 isespecially preferred. Synthetic sodium magnesium silicate clays andfumed silicas can also be used as gelling agents.

The solid gelling agents can be introduced into the aqueous reactantphase as dry powders at any convenient time during its formation.Preferably they will be added after reaction of the particulate abrasivewith the silane coupling agent. In other procedures, the gelling agentis mixed with the balance of the water, e.g. about 30-50% of the totalwater, so as to preform a gel, before it is mixed into the slurriedabrasive. The gelling agent will be used in amounts equal to about2-20%, preferably about 3-15% by weight of this reserved water. Thesuspensions which result are stirred into the abrasive slurry at about25°-30° C. and assist in maintaining the solids in an even suspensionand in stabilizing the emulsion which results when the surfactants andsilicone or fluid are added to the slurried solids. Since a majorportion of the water is lost during the curing process, the addition ofthese amounts of gelling agent to the aqueous reactant phase maintainsthe aqueous emulsion which remains entrained within the cellular matrixin the form of a gel, thus preventing its evaporative loss from the foamsheet. The clays also enhance the polishing properties of the foamwithout embrittling and weakening the cellular matrix as do othersiliceous and aluminous abrasives, such as the feldspars, andsurprisingly produce a stronger cellular matrix than that obtained whenthe resin is foamed in their absence. When present, the polymeric waxcomponent can enhance the polishing ability of the pads by depositing asa thin, smooth film on the surface which is cleaned.

One or more foam-reticulating surfactants will also be incorporated intothe aqueous phase. These surfactants function to remove the windowmembranes of the foam cells, thus producing the desired recticulated, orhighly open, structure. The surfactant also functions to enhance thecleaning power of the finished composition by dispersing greasy dirtwhen the moistened cleaning sheet contacts the soiled area. Foamreticulating surfactants are preferably selected from nonionic typeswhich are soluble or dispersible in water.

Preferred nonionic surfactants include the condensation products ofethylene oxide with a hydrophobic polyoxyalkylene base formed by thecondensation of propylene oxide with propylene glycol. The hydrophobicportion of these compounds has a molecular weight sufficiently high soas to render it water-insoluble. The addition of polyoxyethylenemoieties to this hydrophobic portion increases the water-solubility ofthe molecule as a whole, and the liquid character of the product isretained up to the point where the polyoxyethylene content is about 50%of the total weight of the condensation product. Examples of compoundsof this type include certain of the commercially-available Pluronic®surfactants (BASF Wyandotte Corp.), especially those in which thepolyoxypropylene ether has a molecular weight of about 1500-3000 and thepolyoxyethylene content is about 35-55% of the molecule by weight, i.e.Pluronic® L-62.

Other useful nonionic surfactants include the condensation products ofC₈ -C₂₂ alkyl alcohols with 2-50 moles of ethylene oxide per mole ofalcohol. Examples of compounds of this type include the condensationproducts of C₁₁ -C₁₅ secondary alkyl alcohols with 3-50 moles ofethylene oxide per mole of alcohol which are commercially-available asthe Poly-Tergent® SLF series from Olin Chemicals or the Tergitol® seriesfrom Union Carbide, i.e. Tergitol® 25-L-7, which is formed by condensingabout 7 moles of ethylene oxide with a C₁₂ -C₁₅ alkanol.

Other nonionic surfactants which may be employed include the ethyleneoxide esters of C₆ -C₁₂ alkyl phenols such as(nonylphenoxy)polyoxyethylene ether. Particularly useful are the estersprepared by condensing about 8-12 moles of ethylene oxide withnonylphenol, i.e. the Igepal® CO series (GAF Corp., New York, NY).

Another useful class of nonionic surfactant is especially-preferred forincorporation into the present foams for the ability to foam the waterused to moisten the cleaners. This class includes the amine oxides, suchas the C₁₀ -C₂₀ -alkyl-di(lower)alkyl-amine oxides or the C₁₀ -C₂₀-alkylamino(C₂ -C₅)alkyl di(lower)alkyl-amine oxides. Especiallypreferred members of this class include lauryl(dimethyl)amine oxide,myristyl(dimethyl)amine oxide, stearyl(dimethyl)amine oxide (Schercamox®DMS, Scher Chemicals, Inc., Clifton, NJ), coco(bis-hydroxyethyl)amineoxide (Schercamox® CMS), tallow(bis-hydroxyethyl)amine oxide andcocoamidopropyl(dimethyl)amine oxide (Schercamox® C-AA).

Another useful class of nonionic surfactant is the silicone-glycolcopolymers. These surfactants are prepared by addingpoly(lower)alkylenoxy chains to the free hydroxyl groups ofdimethylpolysiloxanols and are available from the Dow Corning Corp asDow Corning 190 and 193 surfactants (CTFA name: dimethicone copolyol.)These surfactants function, with the silicone fluids, to control thefoaming produced by the other surfactants, and also impart a shine tometallic surfaces.

Other useful nonionics include the ethylene oxide esters of alkylmercaptans such as dodecyl mercaptan polyoxyethylene thioether, theethylene oxide esters of fatty acids such as the lauric ester ofpolyethylene glycol and the lauric ester of methoxypolyethylene glycol,the ethylene oxide ethers of fatty acid amides, the condensationproducts of ethylene oxide with partial fatty acid esters of sorbitolsuch as the lauric ester of sorbitan polyethylene glycol ether, andother similar materials, wherein the mole ratio of ethylene oxide to theacid, phenol, amide or alcohol is about 5-50:1.

The total amount of nonionic surfactant which is used to reticulate thepresent foams is preferably about 0.5-20%, most preferably 1-10% byweight of the aqueous phase.

In addition to one or more nonionic surfactants, the foams used in thecleaning sheets of the present invention will preferably incorporate aneffective amount of one or more anionic surfactants in amounts equal toabout 0.5-5% preferably about 1-3% by weight of the aqueous phase.Anionic surfactants preferred due to their high detergency includeanionic detergent salts having alkyl substituents of 8 to 22 carbonatoms such as the water-soluble higher fatty acid alkali metal soaps,e.g., sodium myristate and sodium palmitate. An especially preferredclass of anionic surfactants encompasses the water-soluble sulfated andsulfonated anionic alkali metal and alkaline earth metal detergent saltscontaining a hydrophobic higher alkyl moiety (typically containing fromabout 8 to 22 carbon atoms) such as salts of higher alkyl mono orpolynuclear aryl sulfonates having from about 1 to 16 carbon atoms inthe alkyl group (e.g., sodium dodecylbenzenesulfonate, magnesiumtridecylbenzenesulfonate, lithium or potassiumpentapropylenebenzenesulfonate). These compounds are available as theBio-Soft® series, i.e. Bio-Soft® D-40 (Stephan Chemical Co., Northfield,IL).

Other useful classes of anionic surfactants include the alkali metalsalts of alkyl naphthalene sulfonic acids (methyl naphthalene sodiumsulfonate, Petro® AA, Petrochemical Corporation); sulfated higher fattyacid monoglycerides such as the sodium salt of the sulfatedmonoglyceride of coconut oil fatty acids and the potassium salt of thesulfated monoglyceride of tallow fatty acids; alkali metal salts ofsulfated fatty alcohols containing from about 10 to 18 carbon atoms(e.g., sodium lauryl sulfate and sodium stearyl sulfate); sodium C₁₄-C₁₆ -alphaolefin sulfonates such as the Bio-Terge® series (StephanChemical Co.); alkali metal salts of sulfated ethylenoxy fatty alcohols(the sodium or ammonium sulfates of the condensation products of about 3moles of ethylene oxide with a C₁₂ 14 C₁₅ n-alkanol, i.e., the Neodol®ethoxysulfates, Shell Chemical Co.); alkali metal salts of higher fattyesters of low molecular weight alkylol sulfonic acids, e.g., fatty acidesters of the sodium salt of isethionic acid; the fatty ethanolamidesulfates; the fatty acid amides of amino alkyl sulfonic acids, e.g.lauric acid amide of taurine; as well as numerous other anionic organicsurface active agents such as sodium xylene sulfonate, sodiumnaphthalene sulfonate, sodium toluene sulfonate and mixtures thereof.

A further useful class of anionic surfactants includes the8-(4-n-alkyl-2-cyclohexenyl)-octanoic acids wherein the cyclohexenylring is substituted with an additional carboxylic acid group. Thesecompounds, or their potassium salts, are commercially-available fromWestvaco Corporation as Diacid® 1550 or H-240.

In general these organic surface active agents are employed in the formof their alkali metal salts, ammonium or alkaline earth metal salts asthese salts possess the requisite stability, solubility, and low costessential to practical utility.

Amphoteric detergents may also be incorporated into these hydrophilicfoams. These detergents will be employed in a compatible proportion andmanner with the nonionic-anionic surfactants, and may comprise about0.5-10%, preferably 1-5% of the aqueous phase.

Examples of amphoteric detergents which may be employed include thefatty imidazolines, such as2-coco-1-hydroxyethyl-1-carboxymethyl-1-hydroxyl-imidazoline and similarproducts made by reacting monocarboxylic fatty acids having chainlengths of 10-24 carbon atoms with 2-hydroxyethyl ethylene diamine andwith monohalo monocarboxylic fatty acids having from 2 to 6 carbonatoms; the fatty beta-alanines such as dodecyl beta-alanine, the innersalt of 2-trimethylamino lauric acid, and betaines such as N-dodecyl-N,N-dimethylamino acetic acid and the like.

Minor but effective amount of fragrance selected so as to bechemically-compatible with the above-described surfactants arepreferably included in the aqueous phase for cosmetic purposes. Usefulfragrances will include, for instance about 0.025-2%, preferably about0.05-1.5% of floral oils such as rose oil, lilac, jasmine, wisteria,lemon, apple blossom, or compounds boquets such as spice, aldehydic,woody, oriental, and the like.

Silicone fluids may also be employed optionally as foam cell initiatingand structuring agents and are selected from those which function tocontrol cell size and aid reticulation. There fluids also function tobreak the foam produced by the surfactants and deposited on the surfacesafter wiping, thus eliminating the need to rinse the surfaces after theyhave been cleaned. Useful classes of silicone fluids include the linearpolymethylsiloxanes or the tetrameric or pentameric cyclic siloxanes(cyclomethicones) which are available from Rhone-Poulenc, Inc. (MonmouthJunction, NJ) as the Rhodorsil® 47V series or from Dow Corning as theDow Corning® 200 fluid series in a wide range of viscosities (i.e.,10-10,000 cps.). When used as a component of the present foams, about0.1-20%, preferably 1-10% by weight of the aqueous phase of a siliconefluid of about 0.5-150 cps viscosity, preferably about 25-100 cps, canbe employed.

Minor amounts of other foam-compatible adjuvants, such as dyes, flameretardants and the like, may be introduced into the present foamproducts in effective amounts either via the aqueous or resin phase orby treating the final product with the adjuvants as by spraying, mixing,etc. When employed in the present products, such adjuvants will commonlybe present at levels of up to about 5-10% by weight of the finishedproduct.

Therefore, the foam component of the present composite cleaners isformed by mixing and foaming the prepolymer resin with the aqueousreactant phase.

A preferred aqueous reactant phase would comprise about 15-35% water,45-65% by weight of abrasive particles which have been surface-treatedwith about 0.1-5% by weight of the abrasive of a silane-coupling agent,about 4-8% by weight of a nonionic surfactant, about 1.5-2.5% by weightof an anionic surfactant, about 2-10% of a silicone fluid and about0.5-15%, preferably about 1-10% of a gelling agent, in admixture withminor amounts of dye and/or fragrance. Preferably the weight ratio ofthe surfactant mixture used will be about 6-1:1 nonionic:anionicsurfactant most preferably about 3-1.5:1. This ratio will be maintainedin the finished cleaning pads since the surfactants are not appreciablyevaporated during the curing step.

To prepare the foam portion of the present cleaning cloths, a warmedaqueous slurry of the particulate abrasive and the silane coupling agentin about 50-70% of the total water is prepared as described hereinabove.The poly(lower)alkylenoxy group-containing nonionic surfactants can thenbe added or they may be added along with gelled balance of the water.The balance of the water, which has preferably been pretreated with agelling agent, is then stirred into the solids slurry, followed byaddition of the remaining surfactants and silicone fluid. Alternatively,the aqueous reactant phase minus the gelling agent may be preformedprior to the addition of the gelling agent.

The stirred aqueous phase is then cooled via the external application ofan ice bath to about 8°-15° C. and the fragrance added. The prepolymerresin, which may be predyed if desired, is then warmed to about 35°-45°C. and blended with the cooled aqueous phase to initiate the foamingreaction. The aqueous phase will preferably be combined with theprepolymer resin in a weight ratio of aqueous phase to prepolymer resinof about 4-2:1. The preferred mole ratio of water to moles of availableisocyanate groups is thereby adjusted to be within the range of about30-60:1. The foaming polymer is then immediately coated onto a textilesheet by conventional methods and allowed to cure without applied heat.Typically, the foaming resin is cured in a closed mold lined on onesurface with a textile sheet.

The amount of foaming resin introduced into the mold is adjusted sothat, as the forming reaction proceeds, the foam expands to fill themold and impregnates and binds the textile sheet. If the expanding uppersurface is compressed to the extent that a skin forms upon curing whichblocks access to the cellular body of the foam, it will be removed, i.e.by slicing, to expose a highly reticulated, porous surface. Therefore,the exposed surface of the foam sheet will be formed or treated so as tobe skinless in the finished cleaning pad.

The textile sheet may be selected from any of the natural or synthetic,woven or nonwoven fabrics which posses sufficient hydrophilicity toremain firmly bonded to the foam layer during use and which possessufficient tensile strength to prevent the foam sheet from cracking orseparating during use. A preferred nonwoven fabric comprises apolyester/rayon blend, most preferably a 70-80% polyester, 20-30% rayonblend such as are available from Crown Textile Co. in weights of about1.0-5.0 oz./yd. Multi-ply textiles may be employed, thus allowing thepreparation of cleaners in which the thickness of the cloth portion isequal to or exceeds that of the foamed sheet. The preferred textilesheets can increase the apparent breaking strength of the foam sheets towhich they are bound by about a factor of 5-15, i.e. from an unboundbreaking strength of about 300-400 g to a composite strength of about3000-4000 g.

The invention will be further described by reference to the followingdetailed examples.

EXAMPLE I

A reaction kettle equipped with turbine stirring was charged with 172.0g of distilled water which was warmed to 28° C., Powdered 200 mesh F-4feldspar (602.4 g) was added with rapid stirring, followed by slowaddition of 3.1 g of n-2-aminoethyl-3-aminopropyl-trimethoxysilane (DowZ-6020). The resultant slurry was stirred for 30 minutes while thetemperature was maintained at 28°-30° C. Pluronic® L-62, Dow® 190 (13.4g) and Tergitol® 25-L-7 (13.4 g) were added with continued stirring.

In a second kettle, 13.4 g of Magnabrite® was added to 115 g of waterand stirred at 45° C. until a gel formed. The gel was cooled to 28° C.and stirred into the feldspar slurry, followed by the sequentialaddition of 17.4 g of BioSoft® D-40, 29.4 g of Schercamox® CAA and 13.4g of Rhodosil® 47V-50 silicone fluid with continued stirring. Theaqueous phase was cooled to 9°-10° C. Lemon fragrance (3.0 g) wasstirred into a 747 g portion of the cooled slurry and 250 g of TRE®standard prepolymer resin which had been preheated to 38°-40° C. wasadded with stirring. After 10 seconds of agitation, fifty gram portionsof the foaming mixture were employed to fill twenty 6.0"×7.0"×0.25"molds. The bottom of each mold was lined with a single, nonwoven sheetof 70-30 rayon/polyester fabric (1.25 oz/yd² ). The molds wereimmediately closed and the foam allowed to cure and bind to the nonwovensheets for 3.5 minutes. The molds were opened and the finished padsremoved and allowed to cool to room temperature.

EXAMPLE II

Similar procedures were employed to prepare foam-coated textile cleanersemploying the formulations summarized on TABLE I, Exs. A and C-E.

To prepare the aqueous reactant phase summarized in Ex. B, 74.4 g ofwater was warmed to 30° C. and 300 g of F-4 Feldspar® added with rapidstirring, followed by the slow addition of 1.55 g of Dow® Z-6020. After30 minutes of stirring at 28°-30° C., the slurry was cooled to 10° C.and the surfactants added, followed by the remainder of the water andthe wollastonite powder. The thick gel was treated with the fragranceand a trace of green dye. The remainder of the procedure followed thatgiven in Ex. 1.

The composite cleaner of Ex. IIC exhibited a breaking strength of 3488 g(elongation at break 75.9%). When cured apart from the textile, a foamlayer of equivalent thickness exhibited a breaking strength of only 350g (elongation at break 109.9%). The breaking strength and elongationvalues represented an average of five runs conducted on an InstronTensile Tester, Model TTC(CRE) according to ASTM D-1682 (2.54 cm cutstrip method).

                  TABLE I                                                         ______________________________________                                        HYDROPHILIC FOAM COMPOSITIONS OF EX. II                                                     Weight Percent                                                  Ingredient      A      B      C    D    E                                     ______________________________________                                        Distilled Water 21.72  18.95  21.72                                                                              21.72                                                                              21.77                                 Magnabrite ®                                                                              1.00   1.00   1.00 1.00 1.00                                  Wollastonite NYAD ® 400                                                                   --     4.07   --   --   --                                    Feldspar        45.23  45.61  45.23                                                                              45.23                                                                              45.23                                 (0.23% Z6020)                                                                 Silicone Fluid (50 cps)                                                                       1.00   --     1.00 1.00 1.00                                  Pluronic ® L-62                                                                           1.00   1.00   1.00 1.00 1.00                                  Tergitol ® 25-L-7                                                                         .80    --     --   --   --                                    Poly-Tergent ® SLF-18                                                                     --     --     --   1.25 --                                    Igepal ® CO-660*                                                                          --     1.25   1.25 --   --                                    Neodol ® 25-35                                                                            --     1.50   1.50 1.50 --                                    Bio-Soft ® D-40***                                                                        1.50   --     --   --    2.30**                               Dow Corning ® 190                                                                         0.25   0.25   0.25 0.25 0.50                                  Schercamox ®  CAA                                                                         2.20   1.75   1.75 1.75 2.20                                  Fragrance       0.30   0.30   0.30 0.30 --                                    TRE STND ® Prepolymer                                                                     25.00  25.00  25.00                                                                              25.00                                                                              25.00                                 ______________________________________                                         *Igepal ® CO710 also gave satisfactory results                            **Equivalent amounts of Biosoft N300, BioSoft D60 or Biosoft ® D35-X      also yielded satisfactory final products.                                     ***1.50% Neodol 25-35 could also be employed in place of the BioSoft .RTM     D40.                                                                     

The composite foam-cloth pads which were obtained possessed an even foamlayer which had a layer of nonwoven fabric firmly bonded to one side.Each fabric sheet had 25-27 g of cured foam adhered thereupon. The padsmoistened readily in water and released a finely-foamed detergentemulsion when either side was applied to a hard surface under conditionsof pressure. After a few seconds, a foam broke, leaving a thin film ofsilicone on the cleaned surface which imparted a shine to plated orpolished metal surfaces. The foam surface strongly absorbed greasy oroily films and removed hardened soil deposits by an abrasive actionwithout depositing a residue of loosened abrasive. The textile sideprovided a nonabrasive surface useful to clean easily scratchedsurfaces.

The composite cleaner of Ex. IID is photographically illustrated in FIG.1 (partial side view, 10× magnification). The open-cellular structure isclearly apparent, as is the highly-reticulated surface of the foamedlayer. The relatively smooth-surfaced nonwoven sheet is clearly shown onthe bottom side of the pad.

As is shown by FIG. 2, which is a photographic 40× magnification of aportion of the foam layer of the FIG. 1 cleaner, the irregular cellvoids are substantially free of particulate matter. The cell windowmembranes of the foam are largely broken and remain adhered to theinterconnecting cell matrix strands in jagged globular masses, producinga foam of high surface area, scouring power and absorbancy. The gelledaqueous phase with its detergent emulsion and the abrasive particles isincorporated integrally with the cellular matrix.

The composite cleaner of Ex. IIB is photographically depicted (partialside view, 10× magnification) in FIG. 3. The open cells of the foamlayer are finer and more uniform in structure than the cells shown inFIG. 1. FIG. 4 is a 40× photographic magnification of a portion of thefoam layer shown in FIG. 3. The highly reticulated nature of theopen-celled foam matrix with its adhered, broken window membranes isclearly shown. The fine, rounded cell voids are highly absorbent andevenly release the surfactant emulsion from the wetted sponge when it isrubbed over a soiled surface.

Since the foam layer shown in FIGS. 1-2 was prepared employing asmectite clay, while the foam shown in FIGS. 3-4 was prepared employingan inosilicate, wollastonite, as the gelling agent, it is expected thatmixtures of the two types of mineral gelling agent will allow theformation of foam sheets having an intermediate cellular structure, e.g.possessing cells which are larger than those depicted in FIGS. 3-4, butwhich are more regular than those shown in FIGS. 1-2. In this manner,both the relative absorbancy and the regularity of the surface of thefoam side of the cleaning pads can be adjusted over a wide range byrelatively simple variations in the composition of the gelling agentused. For example, a blend of about 75-85% wollastonite and 15-25%mortmorillonite will possess a preferred balance between the eveness ofthe cell structure and the reticulation necessary for good scouringpower.

The invention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

What is claimed is:
 1. A composite cleaning pad incorporating opposedfoam and textile surfaces comprising:(a) a sheet of open-celled,reticulated hydrophillic polyurethane foam, the cell walls of said foamintegrally incorporating:(i) a gelled aqueous emulsion comprising anonionic surfactant; and (ii) a coupled particulate abrasive; and (b) atextile sheet covering a surface of said foam sheet and integrallybonded thereto, wherein said foam sheet exhibits a density of about0.2-0.4 g/cc.
 2. The cleaning pad of claim 1 wherein said foam sheetexhibits a breaking strength of about 300-400 g.
 3. The cleaning pad ofclaim 1 wherein said gelled aqueous emulsion comprises an amount of aninorganic gelling agent effective to gel said emulsion.
 4. The cleaningpad of claim 3 wherein the inorganic gelling agent comprises a smectiteclay, an inosilicate mineral or mixtures thereof.
 5. The cleaning pad ofclaim 1 wherein said gelled aqueous emulsion comprises an amount of anorganic gelling agent effective to gel said emulsion.
 6. The cleaningpad of claim 5 wherein the organic gelling agent comprises a polymericwax.
 7. The cleaning pad of claim 1 wherein the emulsion furthercomprises a silicone fluid.
 8. The cleaning pad of claim 1 wherein theaqueous emulsion further comprises an anionic surfactant.
 9. Thecleaning pad of claim 8 wherein the weight ratio of the surfactants isabout 6-1:1 nonionic:anionic surfactant.
 10. The cleaning pad of claim 1wherein the particulate abrasive is coupled into said cell walls with aneffective amount of a silane coupling agent.
 11. The cleaning pad ofclaim 2 wherein the textile sheet is a nonwoven fabric comprising apolyester/rayon blend.
 12. The cleaning pad of claim 11 which exhibits abreaking strength of about 3000-4000 g.